Infrared optical imaging lens, camera module and driving monitor system

Abstract

Provided are an infrared optical imaging camera lens and an imaging device. The lens includes sequentially along an optical axis, from an object side to an imaging side: a stop, a first lens having positive focal power, a second lens having positive focal power, a third lens having negative focal power, and an optical filter. An object-side surface of the first lens is a convex surface, and an image-side surface of the first lens is a concave surface. An object-side surface of the second lens is a concave surface, and an image-side surface of the second lens is a convex surface. An object-side surface of the third lens is a convex surface in a region near the optical axis, and an image-side surface of the third lens is a concave surface in the region near the optical axis.

What is claimed is: 
     
       1. An infrared optical imaging lens, from an object side to an imaging plane along an optical axis thereof, sequentially comprising:
 a stop; 
 a first lens with a positive focal power, an object side surface of the first lens being convex, an image side surface of the first lens being concave; 
 a second lens with a positive focal power, an object side surface of the second lens being concave, an image side surface of the second lens being convex; 
 a third lens with a negative focal power, a paraxial region of an object side surface of the third lens being convex, a paraxial region of an image side surface of the third lens being concave; and 
 a filter; 
 wherein the first lens is a glass lens, the second lens and the third lens are both glass aspherical lenses, and optical centers of the first lens, the second lens and the third lens are positioned in a straight line; 
 wherein the infrared optical imaging lens meets the expressions:
   3.0 mm< f <4.0 mm, 
   −3.0×10 −6 /° C.≤( dn/dt )2≤−0.2×10 −6 /° C. and 3.9×10 −6 /° C.≤( dn/dt )2<8.5×10 −6 /° C., and
 
   3.9×10 −6 /° C.≤( dn/dt )3<8.5×10 −6 /° C.;
 
 
 where f represents a focal length of the infrared optical imaging lens, (dn/dt)2 represents a temperature coefficient of a refractive index of the second lens, and (dn/dt)3 represents a temperature coefficient of a refractive index of the third lens; 
 wherein the infrared optical imaging lens further meets the expression:
   1.393 ≤φ*T   L <1.6; 
 
 where φ represents a focal power of the infrared optical imaging lens, T L  represents a total optical length of the infrared optical imaging lens from the object side surface of the first lens to the imaging plane; 
 wherein the infrared optical imaging lens is applied to a driver monitoring system of a vehicle, and system performance of the infrared optical imaging lens before and after a reflow process with a highest ambient temperature of 230° C.-260° C. is consistent. 
 
     
     
       2. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   0.95<IH/( f *tan θ)<1.05;
 
 where IH represents a half image height of the infrared optical imaging lens, and θ represents a half field of view of the infrared optical imaging lens. 
 
     
     
       3. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   0.7<φ 1 /φ<0.95;
 
 where φ 1  represents a focal power of the first lens. 
 
     
     
       4. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   −2<φ 2 /φ 3 <−1.1;
 
 where φ 2  represents a focal power of the second lens, φ 3  represents a focal power of the third lens. 
 
     
     
       5. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   0.3< R 1/ T   L <0.46; 
 where R1 represents a radius of curvature of the object side surface of the first lens. 
 
     
     
       6. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   0.1<(CT2+ET3)−(ET2+CT3)<0.4;
 
 where CT2 represents a center thickness of the second lens, ET2 represents an edge thickness of the second lens, CT3 represents a center thickness of the third lens, ET3 represents an edge thickness of the third lens. 
 
     
     
       7. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expressions:
   −2.4 <R 3/CT2<−1.5,
 
   −1.6 <R 4/CT2<−1;
 
 where R3 represents a radius of curvature of the object side surface of the second lens, R4 represents a radius of curvature of the image side surface of the second lens, CT2 represents a center thickness of the second lens. 
 
     
     
       8. The infrared optical imaging lens as claimed in  claim 1 , wherein an applicable spectral range of the infrared optical imaging lens is 800 nm to 1100 nm. 
     
     
       9. The infrared optical imaging lens as claimed in  claim 1 , wherein the infrared optical imaging lens meets the expression:
   4.97 mm≤ T   L ≤5.61 mm.
 
 
     
     
       10. A camera module, comprising a barrel, a holder, an image sensor, and an infrared optical imaging lens, wherein the infrared optical imaging lens is mounted in the barrel, the image sensor is mounted in the holder, and the barrel is movably mounted on the holder, the infrared optical imaging lens is configured to form an optical image, the image sensor is configured to generate image data for the optical image sensed thereby,
 wherein the infrared optical imaging lens comprises: 
 a stop; 
 a first lens with a positive focal power, an object side surface of the first lens being convex, an image side surface of the first lens being concave; 
 a second lens with a positive focal power, an object side surface of the second lens being concave, an image side surface of the second lens being convex; 
 a third lens with a negative focal power, a paraxial region of an object side surface of the third lens being convex, a paraxial region of an image side surface of the third lens being concave; and 
 a filter; 
 wherein the first lens is a glass lens, the second lens and the third lens are both glass aspherical lenses, and optical centers of the first lens, the second lens and the third lens are positioned in a straight line; 
 wherein the infrared optical imaging lens meets the expressions:
   3.0 mm< f <4.0 mm, 
   −3.0×10 −6 /° C.≤( dn/dt )2≤−0.2×10 −6 /° C. and 3.9×10 −6 /° C.≤( dn/dt )2<8.5×10 −6 /° C., and
 
   3.9×10 −6 /° C.≤( dn/dt )3<8.5×10 −6 /° C.;
 
 
 where f represents a focal length of the infrared optical imaging lens, (dn/dt)2 represents a temperature coefficient of a refractive index of the second lens, and (dn/dt)3 represents a temperature coefficient of a refractive index of the third lens; 
 wherein the infrared optical imaging lens further meets the expression:
   1.393≤0 *T   L <1.6;
 
 
 where φ represents a focal power of the infrared optical imaging lens, T L  represents a total optical length of the infrared optical imaging lens from the object side surface of the first lens to the imaging plane; 
 wherein the infrared optical imaging lens is applied to a driver monitoring system of a vehicle, and system performance of the infrared optical imaging lens before and after a reflow process with a highest ambient temperature of 230° C.-260° C. is consistent. 
 
     
     
       11. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   0.95<IH/( f *tan θ)<1.05;
 
 where IH represents a half image height of the infrared optical imaging lens, and θ represents a half field of view of the infrared optical imaging lens. 
 
     
     
       12. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   0.7<φ 1 /φ<0.95;
 
 where φ 1  represents a focal power of the first lens. 
 
     
     
       13. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   −2<φ 2 /φ 3 <− 1 . 1 ;
 
 where φ 2  represents a focal power of the second lens, φ 3  represents a focal power of the third lens. 
 
     
     
       14. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   0.3 <R 1 /T   L <0.46; 
 where R1 represents a radius of curvature of the object side surface of the first lens. 
 
     
     
       15. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   0.1<(CT2+ET3)−(ET2+CT3)<0.4;
 
 where CT2 represents a center thickness of the second lens, ET2 represents an edge thickness of the second lens, CT3 represents a center thickness of the third lens, ET3 represents an edge thickness of the third lens. 
 
     
     
       16. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expressions:
   −2.4 <R 3/CT2<−1.5,
 
   −1.6 <R 4/CT2<−1;
 
 where R3 represents a radius of curvature of the object side surface of the second lens, R4 represents a radius of curvature of the image side surface of the second lens, CT2 represents a center thickness of the second lens. 
 
     
     
       17. The camera module as claimed in  claim 10 , wherein the infrared optical imaging lens meets the expression:
   4.97 mm≤ T   L ≤5.61 mm.
 
 
     
     
       18. A driver monitor system, comprising a memory, a processor, and a camera module, the memory and the camera module being electrically connected with the processor, the memory being configured to store image data, the processor being configured to process the image data, the camera module comprising an infrared optical imaging lens and an image sensor, the image sensor being opposite to the infrared optical imaging lens and configured to sense and generate the image data, the infrared optical imaging lens sequentially comprising:
 a stop; 
 a first lens with a positive focal power, an object side surface of the first lens being convex, an image side surface of the first lens being concave; 
 a second lens with a positive focal power, an object side surface of the second lens being concave, an image side surface of the second lens being convex; 
 a third lens with a negative focal power, a paraxial region of an object side surface of the third lens being convex, a paraxial region of an image side surface of the third lens being concave; and 
 a filter; 
 wherein the first lens is a glass lens, the second lens and the third lens are both glass aspherical lenses, and optical centers of the first lens, the second lens and the third lens are positioned in a straight line; 
 wherein the infrared optical imaging lens meets the expressions:
   3.0 mm< f <4.0 mm, 
   −3.0×10 −6 /° C.≤( dn/dt )2<−0.2×10 −6 /° C. and 3.9×10 −6 /° C.≤( dn/dt )2<8.5×10 −6 /° C.,
 
   3.9×10 −6 /° C.≤( dn/dt )3<8.5×10 −6 /° C.;
 
   0.95<IH/( f *tan θ)<1.05; and
 
   1.393≤φ *T   L <1.6;
 
 
 where f represents a focal length of the infrared optical imaging lens, (dn/dt)2 represents a temperature coefficient of a refractive index of the second lens, and (dn/dt)3 represents a temperature coefficient of a refractive index of the third lens; IH represents a half image height of the infrared optical imaging lens, θ represents a half field of view of the infrared optical imaging lens, q represents a focal power of the infrared optical imaging lens, and T L  represents a total optical length of the infrared optical imaging lens from the object side surface of the first lens to an imaging plane; 
 wherein system performance of the infrared optical imaging lens before and after a reflow process with a highest ambient temperature of 230° C.-260° C. is consistent.